Developing drought resilience in irrigated agriculture in the face of increasing water scarcity

In many countries, drought is the natural hazard that causes the greatest agronomic impacts. After recurrent droughts, farmers typically learn from experience and implement changes in management to reduce their future drought risks and impacts. This paper aims to understand how irrigated agriculture in a humid climate has been affected by past droughts and how different actors have adapted their activities and strategies over time to increase their resilience. After examining recent drought episodes from an agroclimatic perspective, information from an online survey was combined with evidence from semi-structured interviews with farmers to assess: drought risk perceptions, impacts of past drought events, management strategies at different scales (regional to farm level) and responses to future risks. Interviews with the water regulatory agency were also conducted to explore their attitudes and decision-making processes during drought events. The results highlight how agricultural drought management strategies evolve over time, including how specific aspects have helped to reduce future drought risks. The importance of adopting a vertically integrated drought management approach in the farming sector coupled with a better understanding of past drought impacts and management options is shown to be crucial for improving decision-making during future drought events

Priorities for sustainable turfgrass management: a research and industry perspective

This paper provides a brief review and assessment of the key environmental, regulatory and technical issues facing the turfgrass sector with specific reference to the European context. It considers the range of externalities or ‘drivers for change' facing the industry, and the challenges and opportunities available for promoting and achieving more sustainable turfgrass management within the sports, landscape and amenity sectors. The analysis confirms that there are a number of key areas where a concerted research and industrial effort is required. These include responding to the pressures from government demands for greater environmental regulation, the increasing pressure on natural resources (notably water, energy and land), the emerging role of turf management in supporting ecosystem services and enhancing biodiversity, the continued need to promote integrated pest management, and the looming challenges posed by a changing climate, and urgent need to adapt. Whilst many of these externalities appear to be risks to the sports turf industry, there will also be significant opportunities, for those where the labour, energy and agronomic costs are minimized and where the drive to adopt a multifunctional approach to sportsturf management is embraced

The economics of irrigating wheat in a humid climate - A study in the East of England

In the UK, wheat is the most important cultivated cereal, grown extensively as a rainfed crop. Irrigation of wheat has previously been considered uneconomic, but increases in world wheat prices and recent droughts have led to some farmers revising their views. Widespread adoption of wheat irrigation would have major implications for wheat production, the irrigation industry and water resources in regions that are already water scarce. This study investigated the financial viability of irrigating winter wheat grown on a sandy loam soil in the East of England. Long-term climate data (1961–2011) for Silsoe (Bedfordshire) was used to drive a biophysical crop model to assess irrigation water requirements and yield response. Modelling assumed a typical irrigation schedule to maximise yield and quality, and average reported wheat prices for 2007 to 2012. Irrigation costs were calculated assuming an overhead mobile hosereel–raingun system applying river water, abstracted either in summer and used directly, or abstracted in winter and stored in an on-farm reservoir. The results suggest that the yield benefit would justify supplemental irrigation by farmers who have unused irrigation equipment and unused summer water, although irrigation of higher-value field vegetable crops later in the season would normally take precedence – the Added Value of Water (AVW) usefully applied to milling winter wheat under these conditions ranged between 0.24 and 0.32 £ m−3. Investment in new irrigation schemes could also be marginally viable if unused summer river water was available for direct abstraction (AVW = 0.08 £ m−3). Investments in new farm reservoirs for irrigating wheat are currently not profitable (AVW = –0.23 £ m−3). Sensitivity analysis suggests that in the longer term, the expected increase in world wheat prices and the impacts of climate change are likely to make the financial benefits stronger, particularly in the drier catchments further east and on low moisture retentive soils, but competing demands for water would still make extensive wheat irrigation unlikely

Climate change impacts on rain-fed and irrigated rice yield in Malawi

There is extensive scientific evidence on climate impacts and adaptation in rice (Oryza sativa L.) but the majority relates to production in south Asia and China. Only a handful of studies have been conducted in Sub-Saharan Africa and none in Malawi. In this paper, the climate impacts on rain-fed and irrigated rice yield have been assessed by combining the downscaled outputs from an ensemble of general circulation models (GCM) (HADCM3, INCM3 and IPCM4) with data from the LARS-WG weather generator to drive the CERES-Rice crop model. This was calibrated and validated using 10 years (2001-2010) field data from three rice schemes to simulate the baseline (1961-90) yield (t ha-1) and then model future yield changes for selected (B1 and A2) emissions scenarios for the 2050s. Although relatively small increases in average yield were projected (+8% and +5% for rainfed and irrigated rice, respectively) there was large uncertainty (-10% to +20% yield change) when considering different GCMs and emission scenario. Farmer responses to cope with the projected impacts include both autonomous and planned adaptation strategies, such as modifying planting dates to maximise crop growth calendars and available soil moisture, increased use of on-farm water conservation measures and land levelling to improve water efficiency in rice schemes dependent on surface irrigatio

Climate change impacts on water for irrigated horticulture in the Vale of Evesham. Final Report

This project has undertaken a scoping review and assessment of the impacts of climate change on irrigated horticulture in the Vale of Evesham, an area of intense irrigated production located within the Environment Agency’s Warwickshire Avon CAMS Catchment. The research was based on a combination of methodologies including desk-based review of published and grey literature, computer agroclimatic and water balance modelling, GIS mapping, meetings with key informants and a stakeholder workshop. Future climate datasets were derived from the latest UK Climate Impacts Programme (UKICIP02) climatology, using selected emission scenarios for the 2020s, 2050s and 2080s. These scenarios were then used to model and map the future agroclimatic conditions under which agriculture might operate and the consequent impacts on irrigation need (depths of water applied) and volumetric demand. This was complimented by a postal survey to abstractors and a stakeholder workshop, to identify, review and assess farmer adaptation options and responses. The key findings arising from the research, implications for water resource management and recommendations for further work are summarised below. Using a geographical information system (GIS), a series of agroclimate maps have been produced, for the baseline and selected UKCIP02 scenario. The maps show major changes in agroclimate within the catchment over the next 50 years. The driest agroclimate zones are currently located around Worcester, Evesham, Tewkesbury and Gloucester, corresponding to areas where horticultural production and irrigation demand are most concentrated. By the 2020s, all agroclimate zones are predicted to increase in aridity. By the 2050s the entire catchment is predicted to have a drier agroclimate than is currently experienced anywhere in the driest parts of the catchment. This will have major impacts on the pattern of land use and irrigation water demand. Cont/d

Water and energy footprint of irrigated agriculture in the Mediterranean region

Irrigated agriculture constitutes the largest consumer of freshwater in the Mediterranean region and provides a major source of income and employment for rural livelihoods. However, increasing droughts and water scarcity have highlighted concerns regarding the environmental sustainability of agriculture in the region. An integrated assessment combining a gridded water balance model with a geodatabase and GIS has been developed and used to assess the water demand and energy footprint of irrigated production in the region. Modelled outputs were linked with crop yield and water resources data to estimate water (m3 kg−1) and energy (CO2 kg−1) productivity and identify vulnerable areas or 'hotspots'. For a selected key crops in the region, irrigation accounts for 61 km3 yr−1 of water abstraction and 1.78 Gt CO2 emissions yr−1, with most emissions from sunflower (73 kg CO2/t) and cotton (60 kg CO2/t) production. Wheat is a major strategic crop in the region and was estimated to have a water productivity of 1000 t Mm−3 and emissions of 31 kg CO2/t. Irrigation modernization would save around 8 km3 of water but would correspondingly increase CO2 emissions by around +135%. Shifting from rain-fed to irrigated production would increase irrigation demand to 166 km3 yr−1 (+137%) whilst CO2 emissions would rise by +270%. The study has major policy implications for understanding the water–energy–food nexus in the region and the trade-offs between strategies to save water, reduce CO2 emissions and/or intensify food production

Difficulties in using spectral properties to map irrigated areas in a temperate climate: A case study of potatoes in England

Irrigation in England is supplemental to rainfall and only used on a small proportion of the cultivated land, notably on high value vegetable and potato crops. However, it is a significant water user as most of the irrigated area is located in the driest part of England. The existing data on irrigated areas are based on government and industry surveys. Recently these datasets have been used with Geographic Information Systems (GIS) to produce irrigated maps, but these can only be published at catchment level due to confidentiality constraints on the datasets. To assess the possibility of using remote sensing data for mapping the irrigated area, one Landsat image for the summer 2003 was used to compare the spectral signature between irrigated and non-irrigated potato fields in the East of England. ISODATA algorithm was used to perform unsupervised classification, and 50 spectral classes were created. A ground truth dataset was then used to identify the most representative spectral class for irrigated and nonirrigated fields. The result showed that categories both fall into the same spectral class, suggesting there are no significant differences between their spectral properties. Therefore, using satellite imagery may not yet be an appropriate method or need more research for mapping irrigated area in temperate climates such as England. The summer rainfall reduces the water stress differences between irrigated and non-irrigated potato fields such that these satellite sensors cannot yet differentiate the crops

Modelling irrigation and fertiliser use for chlorophyll production

Chlorophyll is a natural coloring extract used extensively in the food and pharmaceutical industries. In Europe, most chlorophyll is produced commercially from rainfed grassland production in eastern England. This paper describes a biogeochemical modeling study to assess the potential yield benefits associated with switching from rainfed to irrigated production. The research is in response the impacts of recent summer droughts on yield coupled with risks regarding climate change, rainfall reliability and long-term viability of rainfed production. The Denitrification-Decomposition model was calibrated and validated using multiple field data (n = 47) from 2000 to 2009 for a tall fescue grass (Festuca arundinacea) to simulate a range of irrigation and fertilizer management regimes on yield (annual and individual yield per cut). For chlorophyll production, a schedule combining 300 mm year−1 irrigation with 300 kg N ha−1 was shown to provide the highest average yield (an uplift of +62% above current levels). Switching from rainfed to irrigated production could also potentially halve (54%) current levels of fertilizer application. The implications for reducing environmental impacts from nitrate leaching are discussed

Troubled water

Water forms the basis of one of the Net Positive for Nature targets within the recent RHS Sustainability Strategy. However, while many gardeners may be aware of the water challenges that faced Cape Town in South Africa as it approached ‘Day Zero’ in 2018 or the 2001–2009 Millennium Drought in Australia, why do the RHS and the UK’s 30 million gardeners need to worry about garden water use

Catchment-scale challenges for water resources management: assessing ‘reasonable’ peak needs for irrigated agriculture in a humid climate

Rising demands and competition for water resources within all sectors are placing increasing pressure on the environment. Almost all direct abstractions in England require a licence (permit) from the regulatory authority, the Environment Agency. Assessing and setting ‘reasonable’ peak quantities of water that can be legally abstracted in an environmentally sustainable manner is central to the whole licence determination process. To protect environmental flows and other abstractors within each catchment, the regulatory authority needs to be able to set sensible limits in the licence conditions, including total seasonal volumes and peak rates of water use, particularly for abstractions from hydrologically sensitive surface water sources. This paper describes the development of a methodology to assess the ‘reasonable’ peak rates of water use for agricultural irrigation in support of catchment water resources management and planning. A daily time step water balance model was used to simulate peak monthly and daily water requirements for irrigation using long-term historical weather records for agroclimatically contrasting sites. The model-simulated outputs were then compared against observed data from selected case study farms, and against data reported in a national water abstraction database. Guidelines were then developed for setting peak monthly, daily, hourly, and absolute abstraction rates for irrigation, taking into account the environmental sensitivity of different types of water source. The application of the procedure and its relevance in other countries where catchment water resources are under intense pressure from agriculture are described